1. Technical Field
This invention relates to a high bulk tissue web and method of making and processing a high bulk tissue web. In one aspect, this invention relates to a method of making a high bulk tissue web wound on large diameter parent rolls, unwound for finishing operations, and subsequently rewound.
2. Background
A large diameter manufactured parent roll of bathroom tissue or kitchen toweling can be unwound for finishing operations, such as for calendering, embossing, printing, ply attachment, perforating, or for a combination of two or more finishing operations. The finished bathroom tissue or kitchen toweling then can be rewound into a retail-sized log or roll.
At the time a parent roll runs out, the spent shaft or core can be removed from the machine, and a new roll moved into position by an overhead crane or extended level rails.
Core plugs can support the parent roll on an unwind stand with unwinding power coming from a belt or belts operating on a parent roll surface.
A surface-driven unwind system is not suitable for all types of tissue webs because of a decrease in a machine direction stretch, a reduction of bulk, or damage to the surface of the tissue web, particularly in high bulk tissue webs.
Center driven unwind systems can unwind film.
A down time associated with a parent roll change represents a substantial reduction in total available run time.
The manpower required to change a parent roll reduces the efficiency of a rewinder line and reduces the productivity of neighboring operations when workers are borrowed for roll changes.
Where a finishing unit bonds the expiring web and the new web together, the webs can be threaded manually and advanced. The manual operation reduces efficiencies significantly.
Consequently, a parent roll change reduces the maximum output obtained from a rewinder line and reduces the productivity of neighboring operations as well.
Accordingly, a method for making and processing a web is needed for maintaining preferred characteristics of the web, such as the bulk and the uniformity of the web. A method for making and processing a web also is needed for reducing the time the machine is stopped, to increase overall efficiency, and to provide safety for all personnel.
The apparatus and method of the present invention for making and processing a high bulk tissue web include depositing an aqueous suspension of papermaking fibers onto an endless forming fabric to form a web, drying the web to form a dried web having a bulk of 9.0 grams per cubic centimeter or greater, winding the dried web to form a plurality of parent rolls each comprising a web wound on a core, and transporting the parent rolls to an unwind stand having novel torque transmitting clamping means for engaging opposite end surfaces of the parent rolls. The novel clamping means engage a first parent roll, partially unwind the first parent roll using variable speed drive operably associated with the clamping means, and rotatably support the partially unwound first parent roll on a core placement table adapted to receive the partially unwound first parent roll from the clamping means. Torque transmitting clamping means engage on a second parent roll. A leading end portion of the web on the second parent roll is joined to a trailing end portion of the partially unwound first parent roll by embossing to form a joined web without glue, and the joined web is rewound. The leading end portion of the web on the second parent roll is transported with a thread-up conveyor with vacuum means operably associated with an endless screen belt means.
In one aspect, a novel apparatus and method of making and processing high bulk tissue webs produce a soft, high bulk uncreped throughdried tissue web by depositing an aqueous suspension of papermaking fibers onto an endless forming fabric to form a web and drying the web by throughdrying to final dryness without any significant differential compression to form a dried web having a bulk value of about 15 to 25 cubic centimeters per gram or greater, an MD Stiffness Factor of 50 to 100 kilograms, a machine direction stretch of 15 to 25 percent, and a substantially uniform density.
In one aspect, the apparatus and method of the present invention join a leading end portion of the web on the second parent roll to a trailing end portion of the partially unwound first parent roll to form a joined web without glue in a finishing unit having rolls defining a finishing unit nip, thereafter substantially continuously forming impacts on the web from the first parent roll in the finishing unit nip while the web is unwound from the first parent roll, transporting the web from the second parent roll to the finishing unit, simultaneously passing the webs from both the first and second parent rolls through the finishing unit nip to join the webs together, substantially continuously forming impacts on the web from the second parent roll in the finishing unit nip while the web is unwound from the second parent roll, and rewinding the joined web. The finishing units include an embossing unit, a calendering unit, or a crimping unit.
A torque transfer device for unwinding a tissue roll having a circumferential surface, opposite end surfaces, an inner core surface, an outside diameter of at least about 60 inches, and a width between the opposite end surfaces of at least about 55 inches includes a frame having a pair of arms spaced apart to accommodate the width of the roll, each arm having a side clamping mechanism mounted and adapted to engage one of the opposite end surfaces of the tissue roll, the side clamping mechanism including a backing plate operably connected to and rotatable with an unwind shaft connected to an electric drive, an inflatable bladder mounted on the backing plate, and means for inflating the bladder such that the opposite end surfaces of the roll are sandwiched between the side clamping mechanisms.